Casting box for printing plates



April 10, 1934. R. .1. GREENWAY CASTING BOX FOR PRINTING PLATES Filed Oct. 14, 1932 I L L ATTORNEYS Patented Apr. 10, 1934 PATENT OFFICE I CASTING BOX FOR PRINTING PLATES Richard J. Greenway, Westerly, R. 1., assignor to C. B. Cottrell & Sons Company, Westerly, R. I., a corporation of Delaware Application October 14,

4 Claims.

It has been found that when casting narrow printing plates the pressure exerted by the locking clamps on the top and bottom platens of the casting box beyond the interposed mat and bearers would deflect the corners of the top platen and thereby cause it to spring and bulge in the centre. The object of my invention is to provide means for preventing this springing and bulging of the top platen, irrespective of the size of the plate to be cast.

A practical embodiment of my invention is represented in the accompanying drawing, in which: Fig. 1 represents a top plan view of my improved flat casting box in its closed or clamped position, a mat and its bearers being shown in dotted lines and a portion of the top platen and one of the swinging clamps being broken away at one corner of the box; and

Fig. 2 represents an end view of the casting box in its clamped or closed position, portions being broken away to more clearly illustrate one of the devices for adjustably limiting the movement of the top platen toward the bottom platen beyond the bearers, according to their thickness.

The top platen of the printing plate casting box is denoted by 1 and it may be provided with the usual lifting handles 2. The bottom platen of the casting box is denoted by 3, the mat and the bearers which are interposed between the top and bottom platens of the casting box are donated by 4 and 5 respectively.

The four clamps 6 at the corners of the casting box are shown as hinged at 7 to the bottom platen 3 and as provided with the usual clamp stops 8. The overhanging arms 9 of these clamps 6 carry the manually operated clamp screws 10 which are used for clamping the mat and its bearers between the top and bottom platens in position to permit the casting of the printing plate.

Instead of causing the clamp screws 10 to bear directly upon the top surface of the top platen 1 as is now usual practice, I provide means additional to the mat bearers 5 for limiting the clamping or closing movement of the platens,

said means comprising devices located at the corners of the box beyond the mat bearers, said devices being adjustable according to the thickness of the mat bearers. Each of these devices comprises a cap screw 11 engaging and extending through a threaded hole 12 tapped in the top platen at the corner thereof, the head of which cap screw is preferably provided with a socket 13 for receiving and retaining against lateral displacement the inner end of the clamp screw 10 1932, Serial No. 637,687

when the parts are assembled. The inner end of this cap screw 11 is intended to rest upon the top surface of the bottom platen 3 when the casting box is closed.

An intermediate portion 14 of the shank of the m cap screw 11 is left plain and the top platen is provided with a horizontally disposed set screw 15 arranged in position to engage the non-threaded portion of the cap screw to lock it in its adjusted position as will hereinafter appear.

When it is desired to cast a printing plate the mat 4 and its bearers 5 are placed centrally upon the bottom platen 3 of the casting box. The top platen 1 is then placed on the bearers 5 in register with the bottom platen 3 and the cap screws 11 which limit the .closing movement of the top platen are screwed down until they just contact with the top surface of the bottom platen 3. The set screws 15 are then tightened up and by their engagement with the shanks of the cap screws 11 serve to lock the cap screws in their adjusted positions.

The clamps 6 may then be swung into their operative position and the clamp screws 10 may be screwed down into the sockets 13 in the cap screws with suilicient pressure applied to properly clamp the top platen to the bottom platen and close the box. The parts are then in position to permit the metal to be poured to form the printing plate.

From the above description it will be seen that by this improvement the distortion of the corners of the top platen and the consequent springing or bulging of the top platen under pressure is prevented even When narrow printing plates are to be cast; the cap screws serving as adjustable means for limiting the closing movement of the top platen, according to the thickness of the mat bearers. This will prevent any distortion of the top platen and will ensure its proper contact with the mat bearers to permit the accurate casting of the printing plate.

It is evident that various changes may be resorted to in the construction, form and arrangement of the several parts without departing from the spirit and scope of my invention, and hence I do not intend to limit myself to the particular embodiment herein shown and described, but

What I claim is:

1. In a casting box, top and bottom platens adapted to receive between them a mat and its bearers, platen closing clamps and their screws, and screws carried by the top platen in position to engage the bottom platen and to be engaged by the clamp screws when the box is closed, for 110 limiting the closing movement of the platens beyond the bearers.

2. In a casting box, top and bottom platens adapted to receive between them a mat and its bearers, platen closing clamps and their screws, and screws carried by the top platen in position to engage the bottom platen and to be engaged by the clamp screws when the box is closed, for limiting the closing movement of the platens beyond the bearers, said platen screws being adjustable for bearers of diiferent thicknesses.

3. In a casting box, top and bottom platens adapted to receive between them a mat and its bearers, platen closing clamps and their screws, screws carried by the top platen in position to engage the bottom platen and. to be engaged by the clamp screws when the box is closed, for limiting the closing movement of the platens beyond the bearers, said platen screws being adjustable for bearers of different thicknesses, and means for locking the platen screws in their adjusted positions.

4. In a casting box, top and bottom platens adapted to receive between them a mat and its bearers, platen closing clamps and their screws, screws carried by the top platen in position to engage the bottom platen and to be engaged by the clamp screws when the box is closed, for limiting the closing movement of the platens beyond the bearers, said platen screws being adjustable for bearers of different thicknesses, and set screws for locking the platen screws in their adjusted positions.

RICHARD J. GREENWAY. 

